The present invention relates, in general, to building roofs, and, more particularly, to means for attaching roof panels to building structural members.
Butler Manufacturing Company markets roofs for buildings under the trademarks MR-24 and CMR-24. These roofs include a multiplicity of panels which are seamed together and attached to the building structural elements in a manner which permits movement of those panels to accommodate thermal expansion and contraction.
There are clip units for attaching these panels to the building structural elements such as the roof purlins or the like.
Even though effective, these known clip units have several disadvantages. For example, in a prior clip unit patent application assigned to the same assignee as the present invention, centering structure is provided for holding the roof panel attaching tab centered during initial installation of roof panels on a building. However, once the installation has been completed, it is highly desirable that the tab be permitted to move due to thermal contraction and expansion of the roof panels in use. In the prior application, breakable or fracturable centering structures have been disclosed. However, it has been discovered that even this structure can be improved upon.